1. Field of the Invention
The present invention relates to a tulip contacting device for a vacuum circuit breaker, and particularly, to a tulip contacting device for a vacuum circuit breaker capable of preventing damage of the tulip contacting device and a defective connection and reducing an increase in contact resistance due to vibration or deviation of terminals, by being configured such that a main circuit section terminal is slidably coupled to an under seat of the tulip contacting device.
2. Background of the Invention
In general, a vacuum circuit breaker is a device for protecting an electric power system, in which a vacuum interrupter is made of an arc extinguishing material so as to deliberately perform power transmission/reception, switching, termination and the like and fast perform an automatic blocking of the electric power system when any breakdown occurs.
The vacuum circuit breaker serves to quickly separate (break off, block) a circuit by an arc extinguishing operation by which an arc product generated upon opening and closing a normal load and cutting off a fault current is rapidly dispersed within a vacuum container, thus to protect circuit and other equipment.
Such vacuum circuit breaker is provided with a main circuit section, a truck mechanism (moving carriage), a cradle and an auxiliary element. The truck mechanism is integrally coupled to the main circuit section, and provided with a mechanical part which selectively moves the main circuit section to the cradle.
The coupling or separation between the main circuit section and the cradle is allowed by a tulip contactor of the main circuit section and a cradle terminal of the cradle. During operation in a state of the main circuit section being coupled to the cradle, a current is introduced into a vacuum interrupter installed inside the main circuit section via an upper terminal, and the introduced current is discharged via a lower terminal. During the operation, if any accident occurs, the vacuum interrupter instantaneously cuts off the current.
Here, the tulip contactor includes contact fingers disposed in a circumferential direction to come in contact with circumferential surfaces of a main circuit terminal and a cradle terminal, a circular spring elastically surrounding an outer circumferential surface of the contact fingers, a star plate having a groove at its outer circumferential surface in the circumferential direction such that the contact fingers can be disposed in form of circle, and circular plates disposed at both sides of the star plate to support the contact fingers.
Here, the star plate may serve to fix the contact fingers in the circumferential direction for arrangement and also be fixed to the main circuit terminal by a screw so as to fit the contact fingers to the main circuit terminal.
In the tulip contactor having such configuration, since the circular plates are disposed at both sides of the star plate, the contact fingers are supported at both sides of the star plate in a radial direction, and the star plate is fixed to an outer diameter portion of the main circuit terminal by the screw, the flexibility is degraded after the main circuit terminal is coupled to the cradle terminal.
Also, since the star plate is restricted by the main circuit terminal from being moved in an axial direction, if a perpendicular deviation of the main circuit terminal and the cradle terminal occurs, a defective retraction of the cradle terminal may be caused, thereby interfering with a normal operation of the circuit breaker.
Further, a tension coil spring wound over the contact fingers allows the contact fingers to have contact pressure and simultaneously prevent the contact fingers from being separated from the star plate. Accordingly, upon a disconnection of wire, the arrangement of the contact fingers may become defective.